The study, published today in the Proceedings of the National Academy of Sciences, is the first to demonstrate that "bubbles" of lighter sand form and rise through heavier sand when the two types of sand are subject to vertical vibration
and upward gas flow, similar to the bubbles that form and rise in lava lamps.
- Vertical vibration
reduced for even smoother ride
This is because that the vertical vibration
has a larger amplitude ratio than that of the lateral vibration (Fig.
Because there is a tight coupling between Maglev train and track beam via vertical levitation force for the track beam, it is inevitable to mainly produce vertical vibration
rather than lateral vibration.
For the given body height and vertical step frequency, the pedestrians have to increase the vertical vibration
amplitude as much as possible to habitually keep the ratio of 1/2 between the lateral and vertical step frequencies, which just increases the risk of resonance of the bridge.
According to the International Standard ISO 2631 in the vertical vibration
of the human body, the sensitive range is located in 6 Hz-8 Hz.
The conclusion [16,17] shows SRM vertical force is highly coupled with road excitation and SRM airgap eccentricity, and this coupling yields SRM vertical vibration
that does harm to comfort and stability.
Range of idealized values to characterize seated-body biodynamic response under vertical vibration
part in the setting of (GME/21/6).
In 1995, Ji  proposed a biomechanical continuous bar model to simulate the vertical vibration
of human body.
Those bearings have deficient performance of vertical vibration
mitigation because of the high compression stiffness.